Menstrual fluid simulant

ABSTRACT

Menstrual fluid simulants may consistently emulate the physical characteristics of real menstrual fluid, including but not limited to, viscosity, stringiness, surface tension and size and concentration of particulate matter. In addition, the constituents comprising the menstrual fluid simulants may be changed in order to mimic the variations in real menstrual fluid observed from woman to woman and from an individual woman over time. The menstrual fluid simulants are of use in the testing of personal care absorbent products.

FIELD OF THE INVENTION

Menstrual fluid simulants of use for in vitro testing of femininehygiene products.

BACKGROUND OF THE INVENTION

Personal care absorbent products abound in the market place. Suchproducts are used by persons of all ages and include diapers, trainingpants, adult incontinence articles and feminine hygiene products such astampons and sanitary napkins. Personal care absorbent products are oftensubjected to efficacy testing during the product development phase aswell as to substantiate advertising claims directed to thecommercialized product.

Efficacy testing may be completed in vivo and/or in vitro. In vivo testsmay require panelists to wear a product for a finite time, and thenreturn the used product for data collection and evaluation. In vivotesting can be costly and time-consuming. Moreover, in vivo testingexposes the data collector to the potential risk of contact with bodilyfluids and associated pathogens. In vitro testing can offer a higherdegree of experimental control and precision than in vivo testing. Forthese reasons, in vivo test procedures and artificial body exudates havebeen developed for in vitro testing. For instance, the developers offeminine hygiene products have liquid substitutes for menstrual fluidthat are used in laboratory testing and efficacy demonstrations.

Fluid properties such as surface tension, viscosity, stringiness, andthe size and concentration of particulate matter may affect theinteraction of any fluid with the porous surfaces and absorbentmaterials that form today's highly engineered, high performance femininehygiene products. Many of the conventional artificial menstrual fluidsdo not emulate all of these properties. For example, some artificialfluids are liquid solutions with all of the solids dissolved therein.Artificial fluids that lack solids tend to be absorbed more readily thanreal menstrual fluid, which is a multi-phase suspension of particulatematter in an aqueous liquid. Some artificial fluids do not contain blooddespite observations that real menstrual fluid has properties similar toblood particularly during periods of high flow. Other artificial fluidscurrently in use do not contain mucus or other ingredients necessary toimpart the type of stringy viscoelastic behavior typical of realmenstrual fluid.

In order for in vitro testing of absorbent feminine hygiene products toprovide data that are most directly comparable with in vivo data, themenstrual fluid simulant should closely emulate the physical propertiesof real menstrual fluid. Therefore, a menstrual fluid simulant thatcomprises the properties of real menstrual fluid is desirable.

The fluid properties of real menstrual fluid are highly variable fromwoman to woman and may even vary with regard to an individual woman overthe course of her menstrual period. Therefore, a menstrual fluidsimulant with a composition that can be adjusted to emulate variationsin the properties of real menstrual fluid is also desirable.

SUMMARY OF THE INVENTION

The present invention provides improved menstrual fluid simulants foruse in in vitro testing. Real menstrual fluid contains blood and mucus,yet conventional menstrual fluid simulants are typically formulatedwithout either component. Some conventional simulants utilizereconstituted mucin powder to simulate the properties of mucus. Whenfresh mucus is heated and dried to make mucin powder, the glycoproteinscontained therein may degrade, irreversibly altering its physicochemicalproperties. As such, mucus collected in its hydrated state directly froman animal has better solubility and purity than reconstituted mucinpowder. It has surprisingly been found that mucus substitutes withphysicochemical properties analogous to real mucus may be formulatedwithout using mucin powder. It has surprisingly been found that by usingthese mucus substitutes and/or mucus collected directly from an animal,in combination with a blood product, the menstrual fluid simulants ofthe present invention more accurately replicate the physical propertiesof real menstrual fluid than conventional simulants. In addition, it hassurprisingly been found that the formulation of the menstrual fluidsimulants of the present invention can intentionally be altered to mimicthe naturally occurring variation observed in the physical properties ofreal menstrual fluid.

One embodiment of the menstrual fluid simulant has a general formulationcomprising:

1. a blood product;

2. mucus or a mucus substitute to increase viscosity; and

3. buffer to control pH and electrolyte concentration.

Some single additives may also be added which serve the purpose ofincreasing both viscosity and stringiness. However, separate ingredientsmay be added to enable a degree of independent control over viscosity orstringiness. For example, a high molecular weight polymer may be addedto increase the stringiness of the menstrual fluid simulant.

In some embodiments, the invention is directed to menstrual fluidsimulants comprising from about 5% to about 90% by weight of a bloodproduct; and from about 1% to about 30% by weight of mucus.

In some embodiments, the invention is directed to menstrual fluidsimulants comprising: from about 5% to about 90% by weight of a bloodproduct; and from about 1% to about 30% by weight of a mucus substitute.

In some embodiments, the present invention is directed to menstrualfluid simulants comprising: from about 5% to about 90% of a bloodproduct; from about 1% to about 30% by weight of a gelatin solution;from about 1% to about 30% by weight of an aqueous buffering agent; andfrom about 1% to about 5% of a high molecular weight water-solublepolymer such as polyacrylamide.

The present invention provides a menstrual fluid simulant that mayconsistently emulate the physical characteristics of real menstrualfluid, including but not limited to, viscosity, stringiness, surfacetension and size and concentration of particulate matter. In addition,the constituents comprising the menstrual fluid simulant may beintentionally changed in order to mimic the variations in real menstrualfluid observed from woman to woman and from an individual woman overtime. These and additional advantages will be more apparent in view ofthe following detailed description.

DETAILED DESCRIPTION

The term “blood product” as used herein refers to blood, reconstitutedblood, synthetic blood, red blood cells and combinations thereof. Theterm “blood” is a general term, which encompasses both whole blood andblood that may have had constituents removed from it, such as plasma forexample. Whole blood is blood collected from an animal from which noconstituent, such as plasma, has been removed. Reconstituted bloodcomprises red blood cells that are separated from the other componentsfound in whole blood, which is then reconstituted with plasma, aqueousbuffer, or combinations thereof. The red blood cells may be separatedfrom the other components found in the whole blood via any method knownin the art including, but not limited to, centrifugation (for example at3000 revolutions per minute for 30 minutes), in which case the red bloodcells are referred to as “packed” red blood cells. If reconstituted redblood cells (“packed” or otherwise) are used in the menstrual fluidsimulant (hereinafter referred to as MFS), the red blood cells may beused “as is” or they may be reconstituted to a concentration that isconsistent with that found in the whole blood of the animal from whichthe red blood cells are collected to form reconstituted blood. Syntheticblood may be any synthetic blood known in the art that approximates thephysical properties of human blood, such as being comprised of particlesthat are similar in size to human red blood cells for example.

As used herein, the term “stringy” is interchangeable with the term“ropy” and refers to being viscous and capable of being drawn into athread.

When used herein in relation to liquid compositions, the terms “%” and“percent” refer to the quantity by weight of a component as a percentageof the total weight of the liquid composition, unless otherwiseindicated.

I. Menstrual Fluid Properties

The present menstrual MFS is formulated on the basis of recent advancesin the understanding of menstrual fluid rheology. It has been found thatproperties such as viscosity, stringiness, surface tension and the sizeand concentration of particulate matter can affect the interaction ofmenstrual fluid with the porous surfaces and absorbent materials thatcomprise feminine hygiene articles.

1. Viscosity

Viscosity may affect the acquisition rate of menstrual fluid intoabsorbent structures, such as feminine hygiene products. For example, ifmenstrual fluid viscosity is high, the acquisition rate may be low andinitially the relative amount of fluid available for sorption onto thecontacting surface may be high.

Real menstrual fluid viscosity may range from several centipoises (cP)to several hundred cP. The viscosity of menstrual fluid is highlydependent on shear rate and temperature. The viscosity of the presentMFS is typically measured at a shear rate of 20 sec⁻¹ at 25° C., usingan AR-2000 rotational viscometer from TA Instruments, Newcastle, Del.,with the fluid between parallel plates separated by a distance of 500 to1000 microns. The viscosity of the present MFS may be altered by varyingthe content of mucus, mucus substitute, rheological modifiers andcombinations thereof.

2. Stringiness

When a liquid exists as a thin layer between two adjacent surfaces andthose surfaces are separated, some liquids break cleanly while otherliquids appear to stretch and form “strings” many times the initialliquid thickness. Strings have been observed in biological fluids andare hypothesized to result from the presence therein of high molecularweight species. Human nasal discharge is an example of a viscoelasticfluid that exhibits stringiness under certain conditions. Nasal mucuscan range from being watery to gelatinous depending on the concentrationof mucus in the solution. Saliva normally has a low degree ofelasticity, but as water evaporates on the lips, the concentration ofsalivary mucus rises and stringiness or even slight adhesion of the lipsmay occur.

Real menstrual fluid has varying degrees of stringiness that can beobserved or measured by lifting a glass rod from a collected sample. Theelasticity of menstrual fluid has a rate dependent effect on the way thefluid spontaneously spreads on a surface, is wicked into capillaries infibrous structures, and on the way fluid distributes between surfacesthat are in intermittent contact. If fluid elasticity is very high, itmay exhibit a yield stress behavior where there is no spontaneousabsorption into a capillary structure. Thus the elasticity of realmenstrual fluid is an important determinant in how it interacts with afeminine hygiene product. The stringiness of the present MFS may bealtered by varying content of mucus, mucus substitute, rheologicalmodifiers and combinations thereof.

3. Surface Tension

The surface tension of a fluid impacts its ability to wet the surface ofa feminine hygiene product as well as the ability of the product toabsorb and retain the fluid. Real menstrual fluid is a multi-componentliquid which may contain, among other things, varying amounts of fattyacids, alcohols and glycoproteins, which may have a surfactant-likecharacter that reduces the effective surface tension of the menstrualfluid. The surface tension of real menstrual fluid tends to be similarto blood, but with a greater degree of variability than blood. Water andconventional fluid simulants that are simple aqueous solutions have asurface tension of approximately 73 dynes/cm, whereas the blood plasmathat is found in real menstrual fluid has a surface tension closer toabout 50 dynes/cm. Consequently, it is believed that on a given surface,blood will not bead up as much as water and will tend to spread out to agreater extent.

On the forgoing bases, the MFS of the present invention is formulatedwith a blood product to more closely approximate the surface tension ofreal menstrual fluid.

4. Size and Concentration of Particulate Matter

Particulate matter is commonly found in real menstrual fluid, and maycomprise mucoid and other proteinaceous cell membranes, red blood cellsand agglomerations thereof, the contents of ruptured red blood cells,microorganisms and combinations thereof. Particulate matter can affectthe absorbency of a feminine hygiene article, such as a feminine napkinor tampon, by blocking the pores and capillaries that form the article'ssurface. The size and concentration of particulate matter in realmenstrual fluid may vary widely.

To simulate the particulate matter found in real menstrual fluid, ablood product is used in the MFS of the present invention. Blood,reconstituted blood and red blood cells, packed or otherwise, may beused as they may comprise red blood cells, agglomerations of red bloodcells, as well as ruptured blood cells and their contents. Syntheticblood may be used if it comprises particulate matter that approximatesthat found in mammalian blood. In addition to the blood product, mucus,mucin powder, mucus substitute and combinations thereof, is used in theMFS of the present invention to provide further particulate matter. Forexample, unfiltered gastric mucin solutions contain hundreds tothousands of particles per cubic mm, and the particles in mucin solutionrange from 5 micron in diameter to 50 microns in diameter. Pig stomachmucus also contains insoluble material and in its natural state isopaque due to particulates present. As a result, the MFS of the presentinvention simulates the microscopic appearance and behavior of realmenses.

II. Menstrual Fluid Simulant Compositions

The MFSs of the present invention have surprisingly been found toemulate the physical properties of real menstrual fluid including, butnot limited to, viscosity, stringiness, surface tension and size andconcentration of particulate matter. Moreover, it has surprisingly beenfound that Theological modifiers may be added to the mixture to finetune these properties in order to mimic the variations in propertiesobserved in real menstrual fluid.

In some embodiments of the present invention, the MFS is formulated witha blood product, mucus and an aqueous buffering agent. In otherembodiments, the MFS is formulated with a blood product and a mucussubstitute with properties similar to real mucus. In some embodiments,the physical characteristics of the MFS may be modified through theaddition of rheological modifiers.

1. Blood Products

Menstrual fluid is comprised of blood. The blood content in menstrualfluid may vary from individual to individual and may vary with respectto a given individual over the course of her period. For instance, bloodcontent in menstrual fluid may be lower at the beginning and end of themenstrual period than at the time of highest flow. In order to mimic thephysical and biochemical properties of real menstrual fluid at theheaviest day of flow, or at any other time during the average woman'speriod, the percentage by weight of blood product content of the presentMFS may be from about 5% to about 90%, from about 20% to about 85%, fromabout 30% to about 80%, or even from about 50% to about 75%. Bloodproducts of use include, but are not limited to: blood; reconstitutedblood; red blood cells; synthetic blood; and combinations thereof.

To mimic the physical and biochemical properties of real menstrualfluid, human blood is ideal. However, the use of human blood may becostly and can require strict biohazard precautions to ensure safehandling. Consequently, other types of mammalian blood are of use in theMFS of the present invention.

Mammalian blood is comprised of red blood cells (RBC) which vary in sizedepending upon their source. On average, human RBC vary in size fromabout 8 to about 12 microns (μm) in diameter; swine RBC vary in sizefrom about 6 to about 10 μm in diameter; sheep RBC are about 4.5 μm indiameter; bovine RBC are about 5.5 μm in diameter; feline RBC are about5.8 μm in diameter; canine RBC are about 7 μm in diameter; equine RBCare about 5.7 μm in diameter; and goat RBC are about 4 μm in diameter.Thus, a number of different types of mammalian blood, and combinationsthereof, are of use in the present invention. For example, swine, sheep,bovine, feline, canine, equine, goat blood and combinations thereof maybe of use as safe, less costly alternatives to human blood. Synthetichuman blood and/or synthetic human RBC may also be of use. Anon-limiting example of a synthetic blood simulant is described in EP 1136 824 A1, which is assigned to ProRheo.

If the MFS of the present invention is used immediately after the bloodcomprising it is collected from a mammal, or if the blood productcomprising the MFS does not contain factors that will cause it tocoagulate, then coagulation of the blood may not be an issue. If it isan issue however, then the blood product will have been treated so thatit will not coagulate. This treatment may be any treatment known in theart, including, but not limited to, defibrinating the blood to removethe clotting fibrous materials, the addition of anti-coagulant chemicalsand combinations thereof.

2. Mucus

Real menstrual fluid comprises blood and vaginal mucus. Mucus is anelastic hydrogel of high molecular weight, typically over about 180 kiloDaltons (kDa), and in its natural form is comprised of a solution ofglycoproteins and water. Glycoprotein-based mucus has been identified asa component in real menstrual fluid that is related to the fluid'scharacteristic elasticity (which is measured by stringiness). Real mucusis typically absent in conventional menstrual fluid simulants, andreconstituted mucin powder has often been used in its place. Mucinpowder is conventionally made by grinding, heating and drying animalstomach linings; these processes may degrade the glycoproteins, loweringtheir effective molecular weight and irreversibly altering theirphysicochemical properties. As such, reconstituted mucin powder may notprovide the stringiness provided by mucus that is collected in itshydrated state directly from an animal. It has surprisingly been foundthat by using real mucus in combination with a blood product, the MFSsof the present invention conventional simulants.

Mucus may be collected from various sources. Non-limiting examples ofmucus sources include pigs, hag fish, eels and combinations thereof. Pigstomach mucus is an abundant source of mucus that is chemically similarto human vaginal mucus. Harvested pig stomach mucus may be added to theMFS of the present invention to provide stringiness as well as toincrease viscosity at any shear rate.

The stringiness and viscosity of the present MFS may be varied bychanging the mucus content. The MFS may comprise a percentage by weightof mucus solution of: from about 1% to about 30%; or from about 1% toabout 20%; or from about 2% to about 15%; or even from about 6% to about8%.

3. Mucus Substitutes

Lower cost alternatives to real mucus may be of use in the MFS of thepresent invention. The mucus substitutes of the present invention havesurprisingly been found to closely approximate the fluid properties ofreal mucus, particularly as compared to reconstituted mucin powder.Non-limiting examples of mucus substitutes of use in the presentinvention include: Carbopol® (a Goodrich Chemical Company (Cleveland,Ohio) trade name for a family of water-soluble acrylic acid polymersdistributed by numerous specialty chemical suppliers), sassafras powder,yam powder, psyllium extracts, xanthum gum, guar gum, gelatin andmixtures thereof. Carbopol® 934 is one particular Carbopol® that is ofuse that is distributed by Noveon, Inc., Cleveland, Ohio.

When gelatin is used as a mucus substitute in some embodiments of thepresent invention, the MFS may further be comprised of rheologymodifiers. In some embodiments, the Theological modifiers may be a watersoluble polymer. In some embodiments, the water soluble polymer isanionic-substituted polyacrylamide. From the standpoint of itssolubility and chemical functional groups, the anionic-substitutedpolyacrylamide has similarities to biological polymers. Because of itshigh molecular weight and stability, a very small amount may be added tothe MFS to precisely control the stringiness of the fluid. In oneembodiment of the present invention, the polyacrylamide polymer may bepresent in the MFS in a quantity from: about 25 to 150 to about 300 ppm.The addition of very small amounts of anionic-substituted about 600parts per million (PPM); about 50 to about 400 ppm; or even from aboutpolyacrylamide may increase the viscosity of the MFS slightly, but itincreases its elasticity drastically. This approach may be favored overthose that, while they would work, would require adding largerquantities of less effective polysaccharides or proteins to achievestringiness. Adding large quantities of these additives could alter thebulk chemistry of the MFS.

4. Buffering Agent

To mimic the physical and biochemical properties of real menstrualfluid, an aqueous buffering agent may be of use in the present MFS. Thebuffering agent may serve several purposes. For example, the bufferingagent may maintain the proper biological ionic strength and bufferingcapacity of real menstrual fluid, and the buffering agent may act as adiluent, such as for the mucus and any mucin powder (used as arheological modifier) that is present. Any aqueous buffering agent thatprovides the osmotic pressure of blood and thereby prevents the ruptureof RBC may be of use.

The aqueous buffering agent may be a solution containing approximatelyequal amounts of a conjugate acid/base pair. The aqueous buffering agentmay contain salt and have a pH that is from: about 4 to about 9; or 5 to8; or even 6 to 8. Non-limiting examples of aqueous buffers include:phosphate buffer saline (PBS), which has a pH of about 7.2; potassiumhydrogen phthalate; and potassium phthalate.

5. Rheological Modifiers

The stringiness of real menstrual fluid is highly variable. Somemenstrual fluid samples have no apparent stringiness. Rheologicalmodifiers may be added to the menstrual fluids of the present inventionin order to fine tune their stringiness. Any suitable rheologicalmodifier is of use. Non-limiting examples of rheological modifiersinclude water soluble polymers selected from the group consisting of:polyvinyl alcohols; hydroxyalkyl starches; hydroxyethyl celluloses;hydroxypropyl celluloses; carboxylated latexes; hydroxylated latexes;alginates; polyacrylates; natural gums; modified gums (such as guargum); polyethylene oxide; polypropylene oxide; proteins (such asgelatin); glycoprotein; polysaccharides (such as starch, extracts fromplants, such as okra and sassafras); capsular polysaccharides;polyacrylamides; polyvinylpyrrolidine; cellulose derivatives; mucinpowder; nucleic acids; and combinations thereof. Nucleic acids areselected from the group consisting of ribonucleic acid (RNA),deoxyribonucleic acid (DNA), RNA fragments, DNA fragments, and mixturesthereof. Other high molecular weight proteins that are naturally foundin mucus may also be of use.

In some embodiments of the present invention, mucin powder may also beadded to increase the stringiness of the MFS. Mucin powder may bereconstituted using any suitable means. In some embodiments, a 20%gastric mucin concentrate is made by reconstituting the mucin powder inphosphate buffer, then concentrating it. The resulting gastric mucinconcentrate may then be added to the MFS to a percentage by weight of:from about 1% to about 20%; from about 2% to about 15%; or even fromabout 3% to about 14%.

In some embodiments of the present invention, water soluble polymers maybe added to increase the stringiness of the MFS. Any suitable watersoluble polymer may be of use. Non-limiting examples of water solublepolymers of use include: flocculants such as Superfloc A-150, from CytecIndustries, West Paterson, N.J., USA.

III. Methods of Making MFS

I. Protocol to Prepare Pig Stomach Mucus:

-   1. Collect pig stomachs at slaughter, wash them with tap water and    store in a freezer set at about minus 30° C.-   2. When ready to harvest the mucus, remove the stomachs from the    freezer and allow them to thaw overnight.-   3 Open the stomachs and wash them under running tap water to remove    any feed.-   4. Pin the stomach open on a corkboard and collect the mucus from    the stomach lining by scraping it with a plastic spatula.-   5. Transfer the collected mucus to a previously tared container.-   6. Add an equal volume of a phosphate buffer saline solution (PBS)    with a pH of about 7.2 to the mucus and mix the resulting mixture    with a plastic spatula.-   7. Homogenize the mixture using a kitchen blender at medium speed    for about 2 minutes.-   8. Centrifuge the homogenized mixture at 6000 revolutions per minute    for 1 hour at 4° C.-   9. Remove the supernatant and place it in dialysis tubing with a    12-14,000 molecular weight cut-off, and dialyze against distilled    deionized water for 24 hours in a refrigerator (set at about 40°    C.±4° C.) in order to remove excess salt.-   10. Concentrate the mucus using the same type of dialysis tubing in    a bed of an absorbent gelling material at around 40° C.-   11. Remove the concentrated mucus from the dialysis tubing and keep    it at minus 20° C. until use. The mucus may be thawed and refrozen.    Visually inspect the thawed mucus in order to make sure that it is    homogeneous.    Similar Methods Are of Use for Concentrating Mucus Recovered from    Hag Fish and Eels.

II. Protocol to Prepare Plant-derived Mucus Substitutes

To prepare plant-derived mucus substitutes from sources including, butnot limited to, sassafras, yams or psyllium, the following protocol isused. The mucus-like components are extracted from a plant or itsvegetable using PBS with a pH from about 4.0 to about 10.0. The portionof the plant or its vegetable that contains the mucus-like component isadded to the PBS as a finely ground powder or in small pieces inincrements that would result in a mixture of between about 0.1 and about20% by weight depending on the individual mucus-like containingcomponent. For example, powder from sassafras leaves, yams and/orpsylliums is added to the PBS. The mixture is heated to between about40° C. and about 120° C. and held at temperature for up to an hour. Theresulting mixture is then filtered through a 10 μm nominal filter bag toeliminate any large particles. Upon cooling, the resulting mucussubstitute is then mixed with the other components comprising the MFS ofthe present invention.

IV. EXAMPLES

Exemplary formulations of the present invention are listed in thefollowing tables. The amount of each component present in each MFSformulation is provided as a percentage of the total weight of the MFS.Table 1 provides examples of MFSs comprising mucus. Table 2 providesexamples of MFSs comprising mucus substitutes. TABLE 1 MFS FormulationsComprising Mucus Swine 2% 1% Packed Concen- Gastric Acryl- Acryl- SwineBurro Red trated pig mucin Saline/ Okra amide amide whole whole bloodstomach concen- Phosphate extract in in Example blood blood cells mucustrate buffer solution saline saline Serum Totals 1 71.4% 7.1% 14.4% 7.1%100.0% 2 83.3% 8.3% 8.4% 100.0% 3 83.3% 8.3% 8.3% 100.0% 4 69.0% 6.9%6.9% 17.2% 100.0% 5 69.0% 6.9% 3.4% 20.7% 100.0% 6 71.4% 7.1% 3.6% 17.9%100.0% 7 71.4% 7.1% 1.9% 19.6% 100.0% 8 74.1% 7.4% 18.5% 100.0% 9 83.3%16.7% 0.0% 100.0% 10 67.8% 6.8% 3.4% 16.9% 5.1% 100.0% 11 69.6% 7.0%3.1% 17.4% 3.0% 100.0% 12 69.6% 7.0% 21.9% 1.5% 100.0% 13 72.2% 7.2%1.8% 18.0% 0.8% 100.0% 14 71.1% 7.1% 2.5% 17.8% 1.5% 100.0% 15 50.0%7.9% 42.1% 100.0% 16 50.0% 7.9% 42.1% 100.0% 17 27% 7.1% 2.5% 17.8% 1.5%44% 100.0% 18 28% 6.8% 3.4% 16.7% 5.1% 40% 100.0%

TABLE 2 MFS Formulations Comprising Mucus Substitute 1% 0.5% 0.075% 12%Acryl- xanthum Carbopol ® Gelatin Saline/ amide Swine Burro Sheep gum in934 in in DI Sassafras Phosphate in Example blood blood blood buffersaline water powder buffer saline Totals 15 50.0% 50.0% 100.0% 16 66.7%33.3% 100.0% 17 80.0% 20.0% 100.0% 18 70.0% 7.0% 21.5% 1.5% 100.0% 1970.0% 8.0% 20.5% 1.5% 100.0% 20 70.0% 6.0% 22.5% 1.5% 100.0% 21 50.0%2.0% 48.0% 100.0% 22 50.0% 2.0% 48.0% 100.0% 23 50.0% 2.0% 48.0% 100.0%

The following examples, A, B and C, illustrate how the constituentscomprising an MFS may be adjusted in order to replicate variations inthe properties of real menstrual fluid observed from woman to woman andfrom an individual woman over time. Specifically, the following examplesare different samples of MFSs that are made to have varying viscosities.

Example A

This MFS emulates real menstrual fluid with a viscosity that is measuredas 0.020 Pa sec at 20 sec⁻¹.

71% Defibrinated swine blood

7.1% Pig stomach mucus

2.5% gastric mucin concentrate (27 g gastric mucin powder/450 ml PBSsolution/dialyzed/concentrated)

17.8% PBS solution

1.5% of a 1% solution of Superfloc® 150 in saline

Superfloc™ 150 is an anionic high molecular weight polyacrylamide, whichis available from Cytek Industries, West Paterson, N.J., USA.

Example B

This MFS emulates real menstrual fluid with a viscosity that is measuredas 0.035 Pa sec at 20 sec−1.

70% Defibrinated swine blood

7% Pig stomach mucus

3% gastric mucin concentrate (27 g gastric mucin powder/450 ml PBSsolution/dialyzed/concentrated)

17% PBS solution

3% of a 1% solution of Superfloc™ 150 in saline

Example C

This MFS emulates real menstrual fluid with a viscosity that is measuredas 0.090 Pa sec at 20 sec−1.

69% Defibrinated swine blood

7% Pig stomach mucus

14% gastric mucin concentrate (27 g gastric mucin powder/450 ml PBSsolution/dialyzed/concentrated)

7% PBS solution

3% of a 1% solution of Superfloc™ 150 in saline

IV. Methods of Testing Absorbent Feminine Hygiene Products with MFS

The various embodiments of MFSs of the present invention are of use forin vitro testing of absorbent feminine hygiene products including, butnot limited to, tampons, sanitary napkins and pantiliners. A number ofperformance parameters may be measured by applying the MFS to absorbentproducts. Non-limiting examples of such parameters include absorbentcapacity, run-off or gush and strike through, which may be measuredusing various means including, but not limited to, visual means,gravimetric means, photographic means, using photomicrography andcombinations thereof.

As discussed above, the composition of the MFSs of the present inventionmay be adjusted to emulate the variations in menstrual fluid propertiesthat are observed over the course of a woman's period. Thus an absorbentfeminine hygiene article could be tested for its performance over thecourse of a woman's period, including low flow and high flow days. Forexample, assuming for hypothetical purposes only that the viscosity ofmenstrual fluid varies inversely with the flow of menstrual fluid, asanitary napkin could be tested for its absorbent capacity on: (1) a lowflow day using the MFS from Example C that is very viscous and verystringy; (2) a medium flow day using the MFS from Example B that is lessviscous and very stringy; and (3) a high flow day using the MFS fromExample A that is the least viscous and less stringy.

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this written document conflicts with any meaningor definition of the term in a document incorporated by reference, themeaning or definition assigned to the term in this written documentshall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. A menstrual fluid simulant comprising: a. from about 5% to about 90%by weight of a blood product; and b. from about 1% to about 30% byweight of mucus.
 2. The menstrual fluid simulant according to claim 1,further comprising from about 1% to about 30% by weight of an aqueousbuffering agent.
 3. The menstrual fluid simulant according to claim 1,wherein said blood product is selected from the group consisting of:swine blood; burro blood; human blood; sheep blood; bovine blood;synthetic blood; reconstituted blood; red blood cells and mixturesthereof.
 4. The menstrual fluid simulant according to claim 1, whereinsaid mucus is selected from the group consisting of: pig stomach mucus;hag fish mucus; eel mucus; and mixtures thereof.
 5. The menstrual fluidsimulant according to claim 1, wherein said simulant comprises fromabout 5% to about 20% by weight of said mucus.
 6. The menstrual fluidsimulant according to claim 1, wherein said simulant comprises fromabout 5% to about 25% by weight of said buffering agent.
 7. Themenstrual fluid simulant of claim 1 further comprising rheologicalmodifiers selected from the group consisting of: mucin powder; watersoluble polymers; nucleic acids and fragments thereof; and mixturesthereof.
 8. The menstrual fluid simulant of claim 7, wherein said watersoluble polymer is polyacrylamide.
 9. A method for evaluating theperformance characteristics of an absorbent feminine hygiene product,comprising the step of contacting a first sample of said product with afirst sample of the menstrual fluid simulant according to claim
 1. 10.The method for evaluating the performance characteristics of anabsorbent feminine hygiene product according to claim 9, furthercomprising the step of contacting a second sample of said product thatis different from said first sample of said product with a second sampleof the menstrual fluid simulant according to claim 1 that is differentfrom said first sample of menstrual fluid simulant.
 11. A menstrualfluid simulant comprising: a. from about 5% to about 90% by weight of ablood product; and b. from about 1% to about 30% by weight of a mucussubstitute.
 12. The menstrual fluid simulant according to claim 11,wherein said blood product is selected from the group consisting of:swine blood; burro blood; human blood; sheep blood; bovine blood;synthetic blood; reconstituted blood; red blood cells and mixturesthereof.
 13. The menstrual fluid simulant according to claim 11, whereinsaid mucus substitute is selected from the group consisting of:Carbopol® 934; sassafras powder; yam powder; psyllium powder; xanthumgum; okra extract; polysaccharides; substituted polysaccharides;capsular polysaccharides; protein; gelatin; and combinations thereof.14. The menstrual fluid simulant according to claim 11, furthercomprising Theological modifiers selected from the group consisting of:carboxylated latexes; hydroxylated latexes; polyvinyl alcohol; alginate;polyacrylates; modified gums; polyethylene oxide; polypropylene oxide;proteins; glycoproteins; gastric mucin concentrate; water solublepolymers; nucleic acids and fragments thereof; and mixtures thereof. 15.The menstrual fluid simulant according to claim 13, wherein said mucussubstitute comprises from about 1% to about 30% by weight of a solutioncomprising gelatin.
 16. The menstrual fluid simulant according to claim15, wherein said simulant further comprises acrylamide.
 17. A method forevaluating the performance characteristics of an absorbent femininehygiene product, comprising the step of contacting at least one sampleof said product with at least one sample of the menstrual fluid simulantaccording to claim
 11. 18. A menstrual fluid simulant comprising: a.from about 5% to about 90% by weight of a blood product; b. from about1% to about 30% by weight of a gelatin solution; c. from about 1% toabout 30% by weight of an aqueous buffering agent; and d. from about 1%to about 5% by weight of a 1% solution of polyacrylamide.
 19. Themenstrual fluid simulant according to claim 18, wherein said bloodproduct is selected from the group consisting of: swine blood; burroblood; human blood; sheep blood; bovine blood; synthetic blood;reconstituted blood; red blood cells and mixtures thereof.
 20. Themenstrual fluid simulant of claim 17 further comprising rheologicalmodifiers selected from the group consisting of: gastric mucinconcentrate; water soluble polymers; nucleic acids and fragmentsthereof; and mixtures thereof.
 21. A method for evaluating theperformance characteristics of an absorbent feminine hygiene product,comprising the step of contacting at least one sample of said productwith at least one sample of the menstrual fluid simulant according toclaim 18.